These offspring of F1 hybrids are variable but for some crops this is desirable. F2 hybrids are relatively inexpensive. Pansy ‘Joker Series’ AGM are a widely offered F2 hybrid where the variation compared to F1 hybrids is not considered to be a drawback and whose seed is significantly less expensive than F1 hybrid seed.
When a group of selected plants are grown together and allowed to freely pollinate each other, the seed is said to be open-pollinated. Before the advent of hybrids all seeds were open-pollinated. Open-pollinated seeds are the only option for plants that cannot be easily inbred – lettuces, peas and runner beans for example.
Open-pollinated seed is available for all crops offered as hybrids, but is usually significantly less uniform, vigorous and productive. Open-pollinated seed is relatively inexpensive and can often be readily collected by home gardeners. However, seeds harvested from garden plants will not always come true to their parent, particularly if there is a related plant nearby with which it could have hybridised.
Other hybrids usually sold as plants rather than seed:
Theses are plants produced by crossing different species, for example Viburnum farreri and V. grandiflorum. The resulting offspring are indicated by an × symbol before the species name. This can occur in the wild but more are common in cultivation, as in Viburnum × bodnantense.
These are plants derived from crosses between two or more genera, such as Heuchera and Tiarella. The resulting offspring are indicated by an × symbol before the composite genus name, as in × Heucherella ‘Stoplight’.